PURPOSE: To provide a lighting system for vehicle which can use a HID lamp as a light source of a back-up lamp without increasing the number of HID lamp lighting devices, and can achieve weight reduction, space saving, and cost reduction.

CONSTITUTION: A lighting system for vehicle is provided with a head lamp 2 to illuminate the forward of a vehicle 1 and a back-up lamp 3 to illuminate the backward of the vehicle 1 when the vehicle 1 moves backward, and the head lamp 2 and back-up lamp 3 use HID lamps 5 and 6 as light source, respectively. Then a HID lamp lighting device 4 for lighting the head lamp 2 and back-up lamp 3 is provided to enable selection of lighting mode between the selection lighting of the head lamp 2 and back-up lamp 3 and simultaneous lighting and, when the head lamp 2 and back-up lamp 3 are lit simultaneously, it can supply power distributedly to the head lamp 2 and back-up lamp 3 so that a total power supply to the head lamp 2 and back-up lamp 3 becomes approximately equal to the amount of power supply to one of these lamps.